Printed circuit electrical windings and
inductive apparatus using such windings



March 1, 1966 KILLQRAN 3,238,480

PRINTED CIRCUIT ELECTRICAL WINDINGS AND INDUC'IIVE APPARATUS USING SUCH WINDINGS Filed Aug. 14, 1964 2 Sheets-Sheet l March 1, 1966 KILLQRAN 3,238,480

PRINTED CIRCUIT ELECTRICAL WINDINGS AND INDUCTIVE APPARATUS USING SUCH WINDINGS Filed Aug. 14, 1964 2 Sheets-Sheet z A /B I .C H I G l I I I I I l -c I o United States Patent 3,238,480 PRINTED CIRCUIT ELECTRICAL WINDIN GS AND INDUCTIVE APPARATUS USING SUCH WINDINGS Brian Killoran, Bradford, England, assignor to The English Electric Company Limited, Strand, London, England, a British company Filed Aug. 14, 1964, Ser. No. 389,716 Claims priority, application Great Britain, Sept. 20, 1963, 37,143/63 4 Claims. (Cl. 336- 84) This invention relates to printed circuit electrical winding arrangements and inductive apparatus using such winding arrangements.

According to one aspect of the invention a printed circuit winding arrangement is formed on a flexible sheet of electrically insulating material which also has printed thereon a screen portion which can be folded about the winding to form a screen on either side thereof.

Preferably the screen portion has a printed circuit connection with one end of the winding and includes a printed connection tag by which an external connection can be made to the winding and the screen.

According to another aspect of the invention there is provided a transformer having one or more screened windings made from the printed circuit winding arrangement referred to above.

One form of printed circuit winding arrangement comprising a winding and screen according to the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a plan view of the printed circuit winding and screen on its insulating backing prior to folding to form a screened winding,

FIG. 2 is a plan view of the other side of FIG. 1 showing only the insulating backing,

FIG. 3 is a plan view of one side of the printed circuit of FIG. 1 after it has been folded to form a screened winding, and

FIG. 4 is a general view of a transformer incorporating the winding shown in FIG. 3.

In FIGS. 1 and 2 the reference indicates a sheet of a flexible electrically insulating backing such for example as Mylar polyester film having formed thereon by any suitable printed circuit technique a winding 11 and a. screen portion 12 which is in the form of two open circuited single turns 13 and 14 of which the latter includes a printed connection tag -15. A printed connection 16 is also provided which connects one end of the winding 11 with the screen portion 13 and the other end of the winding 11 has a printed connection tag 17.

Apertures 18, 19, and 21 are cut or punched into the insulating material 10 to accommodate a core when the windings are assembled into a transformer.

FIGS. 1 and 2 are shown with broken lines A, B, C and D along which the printed circuit is folded to form a screened winding and the sections or surfaces between the dotted lines are indicated, in FIG. 1, as J, K, L and M, and in FIG. 2 as E, F, G, H and I. The length of the section L from the line B to the end of that section is shorter than the length of the section I between the line A and the end of that section.

To form the screened winding the printed circuit is first folded along the line A so that the two surfaces E and F face one another with the apertures 18 and 19 in alignment and thus presenting the surface J (FIG. 1) as an outer surface.

The printed circuit is then folded along the line B so that the surface G (FIG. 2) lies adjacent the folded over surface I with the three apertures 18, 19 and 20 in alignment.

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This folding along the line B thus brings the surface L as an outer surface of the winding arrangement with the screen portion 13 on the outside of the winding with the screen portion 14 aligned therewith.

The printed circuit is then folded along the line D to bring the surface I adjacent part of the surface H and the circuit is then folded along the line C to bring the surface H behind the rest of the assembly so that the screen portion 14 is disposed on the other outer side of the winding and the aperture 21 brought into line with the other three aligned apertures.

FIG. 3 which is a view of the complete folded printed circuit formed into a screened winding shows the surface or section L with the screen portion 13 and part of the surface or section I which remains exposed as this section is longer than the section L. A cut-away part of the section I shows the connection tag 15 which it will be noted lies on the same side of the assembly as the connection tag 17.

In assembling the screened winding into a transformer the transformer core passes through the aligned apertures 18 to 21 and alternate windings are assembled and disposed at to one another so that the tags 15 and 17 of adjacent windings are on opposite sides of the assembly. Such an arrangement is shown in FIG. 4 which shows a transformer having a core comprising two C type cores 30, a primary winding which consists of four of the printed windings 31, and eight secondary windings 32 to 39, all in accordance with the present invention.

If desired, the screen of any separate screened winding can be insulated from an adjacent screen but if all the screens are to be connected to the same point, such as an earth point, no insulation will be necessary between screens.

If desired, the connection 16 could be omitted and an additional tag provided for making. contact to the winding.

A transformer having screened windings made as described above is particularly useful for pulse transformers such as are used for firing controllable rectifiers where it is desirable that there should be no capacitative coupling between adjacent windings such as would cause incorrect or unwanted firing of the controllable rectifiers.

What I claim as my invention and desire to secure by Letters Patent is:

1. A printed circuit winding and printed screen arrangement which is capable of being folded to form a flat winding having a screen on either side thereof comprising a sheet of a flexible backing of electrically insulating material, the flexible backing comprising essentially three sections arranged in line with a fourth section projecting at right angles from the third section, each said section being formed with a central aperture, and the third section being slightly shorter in length than the first section, the printed winding being printed on one side of the backing and extending over the first and second sections surrounding the aperture in the first section but not the aperture in the second section, the printed screens being printed on the said one side of the backing and being in the form of two electrically interconnected open circuit turns covering substantially the whole surface of the third and fourth sections about their respective apertures.

2. A printed circuit winding and printed screen arrangement according to claim 1 including a printed circuit connection extending across the said second section of the backing and electrically joining the printed winding to the printed screens.

3. A printed circuit winding and printed screen arrangement which is capable of being folded to form a flat winding having a screen on either side thereof comprising a sheet of a flexible backing of electrically insulating material, the flexible backing comprising essentially three sections arranged in line with a fourth section projecting at right angles from the third section, each said section being formed with a central aperture and the third section being slightly shorter in length than the first section, the printed winding being printed on one side of the backing and arranged to extend over the first and second sections so as to surround the aperture in the first section but not the aperture in the second section, the printed winding including a printed tag connector connected with the inner end of the printed winding and extending over the first and second sections of the backing, and a printed connection printed on the second section of the backing and connecting the other end of the winding with the printed screens Which latter are printed on the said one side of the backing and are in the form of two electrically interconnected open circuit turns covering substantially the whole surface of the third and fourth sections about their respective apertures, the flexible backing including References Cited by the Examiner UNITED STATES PATENTS 2,014,524 9/1935 Franz 336200 2,874,360 2/1959 Eisler 336200 2,911,605 11/1959 Wales 336200 2,943,966 7/1960 Leno et al 336--200 ROBERT K. SCHAEFER, Primary Examiner.

T. J. KOZMA, Assistant Examiner. 

1. A PRINTED CIRCUIT WINDING AND PRINTED SCREEN ARRANGEMENT WHICH IS CAPABLE OF BEING FOLDED TO FORM A FLAT WINDING HAVING A SCREEN ON WITHER SIDE THEREOF COMPRISING A SHEET OF A FLEXIBLE BACKING OF ELECTRICALLY INSULATING MATERIAL, THE FLEXIBLE BACKING COMPRISING ESSENTIALLY THREE SECTIONS ARRANGED IN LINE WITH A FOURTH SECTION PROJECTING AT RIGHT ANGLES FROM THE THIRD SECTION, EACH SAID SECTION BEING FORMED WITH A CENTRAL APERTURE, AND THE THIRD SECTION BEING SLIGHTLY SHORTER IN LENGTH THAN THE FIRST SECTION, THE PRINTED WINDING BEING PRINTED ON ONE SIDE OF THE BACKING AND EXTENDING OVER THE FIRST AND SECOND SECTIONS SURROUNDING THE APERTURE IN THE FIRST SECTION BUT NOT THE APERTURE IN THE SECOND SECTION, THE PRINTED SCREENS BEING PRINTED ON THE SAID ONE SIDE OF THE BACKING AND BEING IN THE FORM OF TWO ELECTRICALLY INTERCONNECTED OPEN CIRCUIT TURNS COVERING SUBSTANTIALLY THE WHOLE SURFACE OF THE THIRD AND FOURTH SECTIONS ABOUT THEIR RESPECTIVE APERTURES. 